EXPERIMENTAL INVESTIGATION INTO ELEMENTARY REACTIONS OF FO RADICALS -THEIR REACTION WITH OZONE AND ITS ROLE IN THE ATMOSPHERIC CHEMISTRY

The reaction of FO radicals with ozone is studied by EPR/IR LMR in a f low reactor. The upper bounds of the rate constants for overall reacti on FO + O-3 1a over right arrow F + 2O(2) 1b over right arrow FO2 + O- 2 are estiamted at k(1a) + k(1b) < 2.10(-16) cm(3).s(-1), T = 300 K an d k(1a) + k(1b) < 4.10(-16) cm(3).s(-1), T = 400 K. The temperatur dep endence of the rate constant is an approximated by expression k(1) < 2 .10(-2) exp(-3400/T) [cm(3).s(-1)]. The results gleaned by this and pr evious studies on the subject are analyzed for the effect of FO reacti ons on depletion of the stratospheric ozone layer. It is demonstrated that the chain of processes leading to ozone destruction in reactions of F, FO, and FO2 is short, because the rate of the FO reaction with o zone is much lower than the rate of its reaction with NO to yield F at oms. This is the main reason why alternative chlorine-free coolants, s uch as CF3CH2F, destroy ozone much less effectively than hydrochlorofl uorocarbons.